Analysis and simulation of the effects of atmospheric turbulence on optical wave propagation.

摘要

This thesis examines the effects of atmospheric turbulence on optical wave propagation between a ground-based transmitter and an orbiting satellite receiver. The simulation that has been developed to model the wave behavior in this environment relies on the refractive-index fluctuation theory developed by Kolmogorov and furthered by Tatarski and Ishimaru. The Gaussian Beam Model is presented as a solution to the three-dimensional wave equation, and the Rytov method is shown to give approximate solutions to the turbulent (stochastic) wave equation. The Gaussian Beam Model is used to give a mathematical structure to the propagating waves, and Kolmogorov's power spectral density function is used to manipulate this Gaussian Beam Model in order to simulate the effects of atmospheric turbulence. The Link Budget equation is included to show that it is possible to determine the optical power received by the satellite without considering turbulence effects, while these turbulence effects can be evaluated as a communication system noise by calculating a parameter known as the "scintillation index." Calculation of the Gaussian Beam parameters and Kolmogorov phase fluctuations is performed in the MatLab programming environment. It is confirmed that, for more efficient optical communication, the following design rules should be followed: longer wavelength, larger transmitter aperture, and higher transmitter altitude.